Safety tip for pneumatic gun



Aug. 2, 1966 0 w. HOPE, JR. ETAL 3,253,934

SAFETY TIP FOR PNEUMATIC GUN I Filfi June 2, 3365 SOURCE OF PNEUMATIC MEDIIUM United States Patent 3,263,934 SAFETY TIP FOR PNEUMATIC GUN Herbert W. Hope, Jr., Huntington-Shelton, and John J. Shuk, Bridgeport, Conn, assignors to Jenkins Brothers, Bridgeport, Conn.

Filed June 2, 1965, Ser. No. 466,501 Claims. (Cl. 239-556) This is a continuatiomin-part application of our earlier application Scr. No. 306,530 filed September 4, 1963, now abandoned.

This invention relates to pneumatic guns of the type intended to eject a stream of a pressure medium at a relatively high force for miscellaneous purposes.

One of the most useful mechanisms which is currently produced relative to the above is a valve which is attached to an air line which may be employed for blowing dust, dirt, chips, filings and the like away from work areas and work pieces.

Strange as it may seem, some operators of the above equipment do occasionally fool or take chances with such pneumatic guns. In fact there have been serious accidents resulting from the application of such guns against and into persons, such as into their ears, against their eyes and so forth. Other accidents have occurred solely as a result of carelessness.

It is an object of this invention to recognize the problems implied by the above and to provide remedial steps calculated to avoid personal injuries due to the misuse of air guns and the like.

More specifically, it is an object of the invention to provide improvements for air guns which prevent, on the one hand, said guns from being inserted into natural body openings and which, on the other hand, avoid the dire consequences of applying a high-pressure stream directly against a body or part thereof.

To achieve the aforegoing and other of its objectives, the invention contemplates the provision, in combination with a means for supplying a pneumatic medium under pressure and second means for controlling the release of this medium, a third means connected to the second means for directing the flow of medium and being of a size to prevent insertion into an opening of less than a predetermined size and being further adapted to provide a main path of flow for the pneumatic medium and an alternate path of flow when the main path is impeded.

In accordance with a preferred embodiment of the invention relative to the above, there is contemplated the provision of a safety tip for an air gun having a threaded discharge opening. This safety tip in accordance with the invention comprises a threaded cylindrical member for engaging in the aforesaid discharge opening and preferably a hexagonal nut member integral with the cylindrical member and in coaxial relationship therewith.

The adjacent cylindrical and nut members are preferably provided with a rectilinear bore extending therethrough, the bore being of a determinable length related to the length of a frusto-conical shell extending from the nut member in coaxial relationship with the latter.

This shell preferably is provided with a first end of smaller diameter than the diameter of its second and free end, the smaller end being connected to the adjacent nut member and being preferably inscribed within the periphery of the latter. The shell has a cone angle varying between 12 and 25 which corresponds to the most efiicient angle at the discharge end of a venturi tube. This will aid in the smooth expansion of the pneumatic medium as it flows through the shell towards the discharge end thereof. The length of this shell is preferably be tween 1 and 2 /2 times the diameter at the larger end, the diameter of the larger end preferably being at least about 1.5 times as large as the smaller diameter. The shell is moreover preferably constituted of a rigid material and is in accordance with a feature of the invention provided approximately midway of its length with at least one lateral opening having a cross-sectional area which is substantially greater than the cross-sectional area of the above noted bore. It is preferred to employ two diametrically opposed equal openings in which the area of each of the openings is at least 5 times the area of the bore and may be as much as times the area of the bore. Thereby the combined area of the lateral openings is between about 10 to 150 times that of the bore. More significantly, however, the area of the openings is related to the outlet area at the larger end of the shell and is generally between 0.4 and 0.6 times said area. This insures a substantial reduction in pressure at the outlet area at the larger end of the shell should such outlet area be blocked.

A further object of the invention is to prevent solid objects from falling into the frusto-conical shell and being accidentally discharged therefrom. This object is achieved by employing air permeable means in the shell to prevent objects from being deposited in the shell through the end thereof of larger diameter while such means is also effective to prevent ejection through the end of larger diameter of any objects which may have become introduced into the shell through said lateral opening.

As will be seen from the description which follows hereinafter, safety tips of the invention are readily fabricated by conventional casting techniques or the like and may be very economically manufactured.

Other objects, features and advantages of the invention will be apparent from the following detailed description as illustrated in the accompanying drawing in which:

FIG. 1 is a pantial sectional view of a conventional gun or valve in association with a source of pneumatic medium and including a conventional tip;

FIG. 2 is a plan view of the air gun of FIG. 1 in association with a safety tip provided in accordance with the invention;

FIG. 3 is a sectional'view of a safety tip provided in accordance with the invention;

FIG. 4 shows the safety tip of FIG. 3 in phantom lines with an insert therein; and

FIG. 5 is an end view of the insert of FIG. 4.

In FIG. 1 is illustrated an air gun or valve 10 in operative association with a source 12 of a pneumatic medium such as compressed air. Said source feeds compressed air to said gun 10 via a hose or line 14 of conventional nature.

The gun 10 comprises generally a valve body 16 to which is pivoted a lever 18 controlling the depression of a spindle 20 against the yieldably resisting force of a spring 22. A valve element 24 is connected to the spindle 20 and controls the discharge ofthe compressed air via a bore 26 in a tip 28 of conventional shape which threadably engages the threaded opening 30 in the valve body 16.

A conventional shop working pressure for the pneumatic medium of FIG. 1 is about to p.s.i. and it is a chief objective of the invention to recognize that guns such as illustrated in FIG. 1 are misused or danger ously employed in various ways leading -to punctured eardrums, damaged eyes and so forth, and to provide a solution for the problems implied thereby.

To this end the invention con-templates the structure such as illustrated in FIG. 2 wherein is shown the gun 10 with a safety tip 32 of the invention substituted for the tip 28 of FIG. 1.

The safety tip of the invention is illustrated in greater detail in FIG. 3. It is seen in this latter figure that said safety tip generally comprises a threaded cylindrical e3 member 34 which constitutes a coupling or connection member by means of which said safety tip is engaged with the threaded opening 30 (FIG. 1) of the associated pneumatic gun.

It is also seen in FIG. 3 that said tip comprises a tightening member 36 which in the preferred embodiment is constituted by a hexagonal nut member integrally connected with cylindrical member 34 and coaxially disposed with respect thereto.

Said members 34 and 36 are provided with a cylindrical bore 38 which constitutes a continuation of the chamber provided within valve body 16 (FIG. I). Said bore isof a diameter d which provides said bore with a cross-sectional area of determinable magnitude.

Finally, the safety tip is provided with a f-rusto-conica-l shell 40 which is connected and preferably integral with the tightening member 36. Shell 40 is preferably coaxially disposed with respect to members 34 .and 36 and with respect to the bore 38 passing therethrough. Shell 40 moreover constitutes an extension of the :bore 3 8 and as well of the chamber within the valve body of the pneumatic gun itself. The shell 40 has within its own geometrical configuration a number of preferred relationships and further has certain geometrical relationships with respect to members 34 and 36 and the bore provided within the same. However, before investigating these relationships, it is essential to note that the shell 40 is provided, approximately midway of its length, with at least one lateral opening 42 and preferably with two of said openings which are diametrically opposed to one another. Moreover, said opening or openings are preferably in the form of a diam-nd to minimize air turbulence in the performance of functions which will hereinafter become apparent.

It is also essential to note that the frusto-conical shell is preferably of a rigid material such as bronze or some other suitable material or the like which will enable the shell to retain its shape despite its being pressed against an external object.

The physical dimensions of a preferred embodiment of the invention include a length of 4" each for the members 34 and 36 along the respective axes thereof. Said shell 40 is preferably of a length L in the order of magnitude of 1%".

Preferably the length L of shell 40 is between 1 /2 and 2 /2 times the diameter at the outlet end 44 of shell 40. This length L will generally be between 2 and times the combined length 1 of the elements 34 and 3-6. This will enable the source of compressed air constituted by the bore 38 to be spaced from any object of a minimum distance which is sufiicient to insure that the foreign body cannot be damaged by compressed air issuing from the bore 38 where the larger end 44 of the shell 40 is blocked. Furthermore, the shell is provided with a cone angle at which 'will be between 12 and 25 and which will produce smooth expansion of the pneumatic medium as it traverses said shell. Moreover the length of shell 40 is of limited length in order that sufiicient velocity of air remains at the outlet end 44 to enable the gun to perform its desired cleaning function.

At the same time the diameter D of the larger end 44 of shell 40 will generally be at least 1.5 times the diameter D of the smaller end 46 of shell 40, which smaller end is connected to the tightening member 36. This relationship assures that the shell 40 can be positioned against a foreign object with some degree of stability without permitting too great a force with which the stream of compressed air is delivered.

In addition, the invention contemplates that the crosssectional area of each of the openings 42 is at least five times the cross-sectional area of the bore 38, while the total area of the openings is between .4 and .6 outlet area at the end 4 4 so that, should the shell 40 be forced against some easily damaged member, the compressed pneumatic medium can be permitted to escape through the openings 42 without causing any significant damage to the foreign element referred to.

From what has been indicate-d above, it will now be appreciated that the shell 40', in conjunction with elements 34 and 3-6, constitute the means [for connection to an air gun or the like, which means enables the directing of the flow of the pneumatic medium while at the same time being of a size to prevent insertion into an opening of less than a predetermined size and being moreover adapted to provide a main path of flow for the medium and an alternate path of flow when the main path is impeded.

As a result of the above provisions, the invention is enabled to achieve its objective of preventing air guns and the like from being inserted into natural body openings and to avoid the dire consequence of applying a high pressure stream directly against a body or a part thereof.

In tests which have been conducted to demonstrate the efiectiveness of the safety tip according to the invention, a tip having the following approximate dimensions was tested:

Two diametrically opposed openings 42 of a parallelogram shape were centrally located along the length L of shell 40 and therefore had a center at a distance of from the end of largest diameter D. Each opening 42 had a diagonal dimension as measured lengthwise along a generatrix of the frusto-conical shell of and a transverse diagonal dimension of The shell had a thickness of about Such a tip was compared in con-junction with a conventional type of nozzle of the form generally shown in FIG. 1 with a nozzle opening of 1 For the test of the tip and nozzle a fixture was constructed whereby air expelled from the type of nozzle tested could be accurately read on sensitive pressure gauges in pounds per square inch. When in direct contact with the measuring instrument the conventional pneumatic nozzle registered approximately the full lbs. air line pressure which was supplied to the nozzle. A pressure test through one-half inch free air produced gauge readings of 60 lbs., and at one inch readings of 30 lbs. per sq. inch were obtained.

When the aforesaid safety tip was placed in sealed contact with the gauge, i.e., the outlet diameter was blocked, there was produced a maximum pressure of 1.75 lbs. per sq. inch from a line delivery of 90 lbs. of accurately regulated air pressure.

Based on these findings the safety tip tested exhibits a factor of safety of 98.06% over the ordinary pneumatic gun nozzle.

Further tests were conducted with an ordinary medicinal bowl type syringe and it was established that such syringes can develop air pressure of up to 3 lbs. per sq. inch, or 41.67% greater pressure than the maximum pressure delivered by the aforesaid safety tip.

From the above it is readily apparent that there has been effected a substantial elimination in the discharge pressure whereby any danger of accident resulting from application of the shell against a person is overcome. Moreover, the increased diameter at the larger end of the shell prevents insertion of the safety tip into natural body openings. Furthermore, all of the above is achieved while there is maintained sufficient air velocity at the discharge end of the shell to enable the gun to be employed for its normal cleaning function.

In further accordance with the invention there is employed an insert 50 of spider shape which is disposed at the outlet end 44 of the shell 40 and is adapted for preventing entry of solid objects into the shell 40 through the opening at the outlet end. Furthermore, the insert 50 prevents discharge through the outlet opening of any objects which may have become inserted through openings 42. Preferably, the insert is integrally cast with the frusto-conical shell 40 in order to prevent its removal which would defeat its safety function. However, it is also possible to employ an elastic insert such as polyethylene which when forcibly inserted into the shell is sufficiently deformed so as to make its removal quite difficult and thereby discourage such removal.

The insert has a central dish portion 51 of ring shape from which radiate legs 52. There are shown a total of twelve legs which define spaces between adjacent legs which are sufficiently small in order to prevent discharge through outlet end 44 of an object which can be supported in the smaller end 46 of shell 40 adjacent bore 38. T he maximum distance between opposed surfaces of adjacent legs should be less than the diameter of bore 38 in order to prevent discharge through the outlet end of any objects which could be supported at the smaller end 46 of shell 48 without falling in the bore 38. Although twelve legs have been shown, a greater or lesser number may be employed as desired, as long as the clear space between adjacent legs is less than the diameter of bore 38. A rim 53 supports the ends of the legs 52. The insert is sufliciently air permeable in order not to interfere with the normal fiow of air through the shell. In this respect, the legs may be replaced with a mesh construction or the like, which would permit normal flow while also serving to exclude entry into the shell of relatively small size material at the outlet end 44 of the shell 40.

The spider is located at the outlet end 44 of the shell 40 and serves to prevent discharge at high velocity of any object which may have been introduced through opening 42 and was initially positioned at the outlet of bore 38. Thereby such object is prevented from being discharged as a projectile from the shell. Any object which is initially positioned so as to be supported on the spider would be sufficiently distant from bore 38 to receive only slight force and hence extremely low discharge velocity, if any, from the shell. Consequently, such object could never act as a projectile.

There will now be obvious to those skilled in the art many modifications and variations of the structure set forth above. These modifications and variations will not, however, depart from the scope of the invention if defined by the following claims.

What is claimed is:

1. A safety tip for a gun having a discharge opening for a high pressure fluid medium, said safety tip comprising a frusto-conical shell having an inlet extending in continuing relationship with said opening to directly receive the fluid medium therefrom, said shell having a flat planar edge at the end of larger diameter which constitutes an outlet opening for the fluid medium, said shell being of a rigid material and being provided, approximately midway of the length thereof, with a pair of diametrically opposed openings, each having a cross-sectional area between 5 and 75 times the area of the inlet to permit free discharge of said fluid medium with said outlet opening blocked, said shell having a cone angle between 12 and 25 and a length which is between 1% and 2 /2 times the diameter of the shell at the end of larger diameter, such that the larger diameter is at least about 1.5 times as large as the smaller diameter, the cross-sectional area of the openings being between 0.4 and 0.6 times the area of the shell at the end of larger diameter.

2. A tip as claimed in claim 1, comprising air permeable means in said shell for preventing objects from reaching said inlet while preventing discharge of any objects through the end of larger diameter of the shell.

3. A tip as claimed in claim 2, wherein said air permeable means is a spider-like insert disposed in the shell adjacent said end of larger diameter.

4. A tip as claimed in claim 1, wherein said openings are of diamond shape with diagonally opposite corners extending along a generatriX of the frusto-conical shell.

5. A safety tip for an air gun having a threaded opening, said safety tip comprising a threaded cylindrical member for engaging in said opening, a hexagonal nut member integral with said cylindrical member in coaxial relationship therewith, said members being provided with a rectilinear bore extending therethrough for receiving high pressure air from said gun, said bore being of a determinable length, and af frusto-conical shell extending from said nut member in coaxial relationship therewith and in continuing relation with said bore, said shell having a length of about two to five times that of said bore, said shell having a first end of smaller diameter connected to the nut member and inscribed within the periphery of the latter and a second end of larger diameter constituting a free end for the discharge of air therefrom, the larger diameter being at least about 1.5 times as large as the smaller diameter, said shell having a flat planar edge at said second end, said shell being of a rigid material and being provided, approximately midway of its length with a pair of diametrically opposed openings, each of diamond shape and of cross-sectional area between 5 and times that of said bore, said openings having a cross-sectional area between 0.4 and 0.6 times the area of the shell at the end of larger diameter, the diamond shape openings having diagonal corners extending along a generatrix of the frusto-conical shell.

References Cited by the Examiner UNITED STATES PATENTS 606,093 6/1898 Semke 15406 X 1,020,207 3/1912 Kells 137--381 2,556,878 9/1951 Fahrenkrog et al. 15406 3,063,25 8 11/ 1962 Szachnitowski.

FOREIGN PATENTS 13 0,060 6/ 1947 Australia. 212,799 3/ 1924 Great Britain.

M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Examiner. 

1. A SAFETY TIP FOR A GUN HAVING A DISCHARGE OPENING FOR A HIGH PRESSURE FLUID MEDIUM, SAID SAFETY TIP COMPRISING A FRUSTO-CONICAL SHELL HAVING AN INLET EXTENDING IN CONTINUING RELATIONSHIP WITH SAID OPENING TO DIRECTLY RECEIVE THE FLUID MEDIUM THEREFROM, SAID SHELL HAVING A FLAT PLANAR EDGE AT THE END OF LARGER DIAMETER WHCIH CONSITUTES AN OUTLET OPENING FOR THE FLUID MEDIUM, SAID SHELL BEING OF A RIGID MATERIAL AND BEING PROVIDED, APPROXIMATELY MIDWAY OF THE LENGTH THEREOF, WITH A PAIR OF DIAMETRICALLY OPPOSED OPENINGS, EACH HAVING A CROSS-SECTIONAL AREA BETWEEN 5 AND 75 TIMES THE AREA OF THE INLET TO PERMIT FREE DISCHARGE OF SAID FLUID MEDIUM WITH SAID OUTLET OPENING BLOCKED, SAID SHELL HAVING A CONE ANGLE BETWEEN 12* AND 25* AND A LENGTH WHICH IS BETWEEN 1 1/2 AND 2 1/2 TIMES THE DIAMETER OF THE SHELL AT THE END OF LARGER DIAMETER, SUCH THAT THE LARGER DIAMETER IS AT LEAST ABOUT 1.5 TIMES AS LARGE AS THE SMALLER DIAMETER, THE CROSS-SECTIONAL AREA OF THE OPENINGS BEING BETWEEN 0.4 AND 0.6 TIMES THE AREA OF THE SHELL AT THE END OF LARGER DIAMETER. 